hey.........

to determine

basic strength: ..........we have to see.........the stability of its conjugate............

add

 

H+ to aniline it becomes NH3+  ............................and check its

stability  OR.........IS A +R effectiing group ............therefore it will produce  negative charge..............and stabilize it...............same with ortho................

but for meta charge   -  will not come...............

 

therefore basic strength goes:

 

para  >  ortho  >  aniline  >  meta............

 

hope i m clear...............

thanku